(1) Field of the Invention
The present invention relates generally to single chain fragment variables (scFv) antibody molecules. Specifically, the present invention relates binding scFv antibody molecules on a substrate that can bind an analyte of interest to the surface.
(2) Description of the Related Art
Antibodies and antibody-based reagents are used in immunotherapy and solid phase based applications including biosensors, affinity chromatography, and immunoassays. In 1988, Phage display technology was developed that allows the presentation of large peptide and protein libraries on the surface of filamentous phage, which leads to the selection of antibodies and antibody fragments, with high affinity and specificity to almost any target. The smallest such antibody fragment is the Fv, which is obtained by association of the variable domains of the heavy chain (VH) and the light chain (VL) of the antibody. Without the accompanying Fc region, Fvs can dissociate rapidly into their single domains, VH and VL and results in a complete loss of the function of the Fv. Protein engineering, recombinant DNA cloning and expression techniques allow the production of small Fvs, which have the domains of the heterodimers stabilized in various ways. For example, recombinant Fvs may contain flexible inter- or intra-chain linkers, connector's peptides, or extra disulfide bonds, and they often fully retain the binding specificity and affinity of the corresponding antibody. Many scFvs retain the specificity and have similar affinity with the original antibody or the monovalent Fab fragment. The advantages of the phage-displayed recombinant antibodies over the conventional polycolonal or monocolonal antibodies are quick generation time, cheap production cost, and importantly, accessibility to the antibody DNA for further genetic manipulations. However, their long circulating half-life is a disadvantage for tumor imaging and therapy. Furthermore, without Fc portion, it cannot initiate immunoresponse. Typically, the scFvs were conjugated with a drug to target tumor cells. However, combining scFv with drugs may increase the chance of toxicity.
While the related art antibodies bound to solid substrates, there still exists a need for an improved system that can immobilize scFv to the sensor substrate (such as Au) so that it can bind analytes of interest to a substrate.